There are many reports indicating the presence of various trace organic contaminants in treated wastewater and other water sources. The detection of such contaminants in environment and the ability of these contaminants to pose potential threats to environment at very low concentrations have led to a need for more efficient treatment technologies. Cyclodextrins (CDs) have gained significant interest as alternative adsorbents for water and waste water treatment because of their unique physico-chemical characteristics and excellent selectivity towards organic compounds and metals. The property of CD to form inclusion complexes with various molecules through host-guest interactions has made it a useful compound for the removal of a number of contaminants from water and wastewater. In this research, a hybrid adsorbent was synthesized by coating β-cyclodextrin (BCD) onto silica and was tested for the removal of selected trace organics. 17β-estradiol (E2), perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS) and bisphenol-A (BPA) were selected as model contaminants to represent the trace organic contaminants. The adsorbent showed more than 95% removal of E2, PFOA and PFOS and upto 90% removal of BPA in Milli-Q (MQ) water. These experiments were done at initial concentrations ranging from 25 - 100 µg/L, which are much higher than they have been reported in environmental samples. In order to represent the real environmental concentration of ECs, further experiments were conducted at initial concentration of 500 ng/L for each contaminant in MQ water. These results were compared with the performance of the adsorbent in real wastewater by spiking the same concentration in secondary effluent of a municipal wastewater treatment plant. The adsorbent was effective in removing more than 99% of both PFOA and PFOS from MQ water at adsorbent dosage of 1.5 g/L where as the adsorbent removed 90% of PFOS and 85% of PFOA from wastewater at adsorbent dosage of 2.0 g/L. A sustainable way of regenerating the adsorbent was developed where ozone was used to destroy the contaminants trapped in the saturated adsorbent there by regenerating the adsorbent for reuse. This regeneration process without generating any waste was very effective in regenerating the adsorbent over seven successive cycles for the removal of BPA and E2 without significant loss in its adsorption capacity.

Preparation and evaluation of hybrid adsorbent for the removal of trace organic contaminants from water and wastewater

249th National Meeting (2015)

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